نشریه پژوهش های نوین فیزیک
سال چهارم شماره 2 (پیاپی 7، پاییز و زمستان 1398)

Ag nanoparticles were deposited using the chemical method of Tollens to have silvery active substrates which they were utilized in Surface Enhanced Raman Spectroscopy (SERS) to detect phenylalanine, beta-alanine, leucine and glycine amino-acids. Silvery active SERS substrates were characterized using UV-Vis spectroscopy, X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). Plasmonic peak at around 439 nm in UV-Vis spectrum as well as FCC structure in XRD spectrum confirmed the formation of Ag structures. According to the FE-SEM image, although the most Ag particles have the sizes between 100 - 300 nm, particles with the smaller size of 50 nm and the larger size of 1000 nm have been synthesized. The presence of the large particles causes the light scatters from them. Then, different concentrations of the amino acids were engraved on the active SERS substrates to detect their molecular vibrations using Raman spectroscopy. The molecular vibrations of the amino acids are enhanced when they were engraved on the active SERS substrates due to surface plasmon resonance of the smaller Ag nanoparticles as well as light scattering from the larger Ag particles. In the other hand, the SERS intensity of the amino acids are stronger than their Raman intensity. The active SERS substrates could identify the concentration of 10-7 M of the amino-acids.

The two-dimensional, transition metals dichalcogenides (TMDC) layers with straight band gaps have created a new horizon in the use of these materials in photonics and electroptics. In this paper, the effects of the thin layer and the effects of the spacer have been investigated. The optical properties of structures are investigated by the transfer matrix method, TMM, in the visible wavelength region. By looking at the optical features of the structure with spacer the absorption increases. We have been able to achieve an absorption above 99% with thickness of plasmonic layer 75 nm and thickness of spacer 33 nm for MoS2 and 40 nm for MoSe2.

In this paper, considering a two-dimensional square potential well with infinite walls (i.e. an impenetrable container), the collision force originated from a confined quantum particle which is exerted on the objects within the container is numerically calculated. The objects within the container are modeled as small barriers and wells. For the case of single object, calculations show that depending on the kind of the object and its position within the container and also the shape of the wave function of the confined particle, different forces are acted on the object. The forces are dependent on the spatial variations of the confined particle energy. When more than one body is located within the container the acted force on each object produces a kind of apparent attractive or repulsive force among them. Presence of an external potential in the container space (such as gravitational potential of the earth) is also effective on the collisional force acting on the objects and causes a net force in the direction of the gradient of the external potential (like Archimedes buoyancy force) or in its opposite direction.

Cadmium sulfide nanoparticles are synthesized from the reaction of Cadmium sulfate pentahydrate, as the sources of producing Cd2+ ions, various sources of brimstone, as the sources of producing S2- ions, and a specific amount of Polyethylene glycol 400, as a recovering factor in the in different PHs and different temperatures, using the hydrothermal manner.The samples are characterized by use of an inspecting spectrum, X-ray diffraction , Fourier transform of infrared, scanning electronic microscope, analyzing diffracted X-ray and Transmission electron microscope. Assessing the spectrum of diffraction X-ray shows that the samples have a hexagonal structure in different PHs and different temperatures and samples have hexagonal structure and qubic structure in various sources of brimstone. the absorbed wavelength in all samples were below the Balk state and It has a red shift by use of thioacetamide sault, as the resource of S, due to the production of nanoparticles in different sizes. In addition, the existence of peaks related to vibrational modes of Cadmium sulfide is confirmed using the FT-IR pictures. Our studies demonstrate that the sizes of nanoparticles increase when PH and temperature increases. According to the calculation carried out, the energy gap of nanoparticles in all samples it is upper than the Bulk state. In assessing the nanoparticles synthesized using SEM, it is shown that the structure of nanoparticles change from nanorods to spherical as PH increases and it is shown the structure of nanoparticles is nanorods in different temperatures. In assessing the nanoparticles synthesized using various sources of brimstone by use of SEM,it is shown that the samples have spherical, nanorods and clustered structure.

The creation of inadvertent steady streaming vortices inside microchannels under the effect of an external ultrasound field is a nonlinear phenomenon that was known as a troublesome effect in acoustophoretic manipulation of microparticles. In recent years this phenomenon has been treated properly and has turned into a very useful parameter in acoustic tweezing of submicrometer particles or micromixing of fluids in acoustofluid systems. The geometry of the fluid container plays a key role in the shape of acoustic streaming patterns. Because of the complexity of this effect, numerical calculations need to be carried out and predict the most convenient design for special applications. In this paper, we investigate the effect of sinusoidal as well as the toothed sidewalls of microchannels on acoustic streaming patterns and compare them with the effects of the flat sidewalls. The pattern of the three large vortices has observed in the bulk of sinusoidal and toothed microchannels in specific dimensions. Such a pattern was not achievable in a flat geometry. It allows for sinusoidal and toothed channels with a specific geometric range, to have the application of fluid mixing or particle trapping.

This paper dealt with design and simulation of one of the most important electrical computational basic circuit. The half-adder is simulated with knowledge and use of the interaction of three spatial optical solitons that was the foundation of complex processor circuits and can be a good candidate to use in the future of photonics and optical computation. The inputs of the designed logical circuit are three spatial solitons that enter into a nonlinear Kerr medium, and by adjusting their initial phase, attraction and repulsion interactions occur between the solitons and the desired performance of the half-adder circuit is obtained. Simulation of the solitonchr('39')s propagation was performed using the Fourier split-step method. This study demonstrates that the spatial solitons interactions have many useful capabilities that can be the solution to optical computing and optical data processing and to overcome the problem of increasing the speed of electronic circuits. The introduced half-adder logic circuit is one of them and the proposed method can be used to design the other logical circuits.

a theory that is equal to Einstein’s gravity up to the third order in curvature in the linear limit of field equations in a vacuum which is called Einsteinian cubic gravity has been introduced. This theory contains Einstein’s standard term, cosmological constant, Gauss-Bonnet and third order curvature terms.In this paper, we will find answers of this theory in four dimensions, in which space and time behave differently under the scale conversions. To find these kind of solutions, We used the Lifshitz metric with hyperscaling violation with θ and showed that in cubic gravity, the are black hole solutions with hyperscaling violation  for any arbitrary value of z and only for θ = 2 in four dimensions. Also we will see that for this black hole thermodynamic quantities such as temprature and entropy are zero.